Gas detector for steam condensate and cooling tower water systems



Feb. 26, 1963 w. H. MAGEARL EIAL GAS DETECTOR FOR STEAM CONDENSATE AND COOLING TOWER WATER SYSTEMS 4 Sheets-Sheet 1 Filed Feb. 18, 1957 muaoh nllltlllllll 02:08 2.

ne nn William H. Mogeorl tors Robert E. Nelson, Jr.

My Attorney Feb. 26, 1963 w. H, MAGEARL EIAL GAS DETECTOR FOR STEAM CONDENSATE AND COOLING TOWER WATE SYSTEMS 4 Sheets-Sheet 2 Filed Feb. 18, 1957 FlG.-2

William H. Mugeorl Inventors Robert E. Nelson, Jr.

By Attorney Feb. 26 1963 W.-H.IMAGEARL EI'AI. 3,078,918

GAS DETECTOR FOR STEAM CONDENSATE AND COOLING TOWER WATE SYSTEMS Filed Feb. 18, 1957 4 Sheets-Shqet 3 J, FlG.-3

williom H. Mugeorl Robert E. Nelson, Jr.

By Attorney lnvemors,

Feb. 26, 1963 w. H. MAGEARL ETAL 3,078, 1

GAS DETECTOR FOR STEAM CONDENSATE AND COOLING TOWER WATER SYSTEMS il d F 18, 1957 4 Sheets-Sheet 4 zISB )JJAAAAAAA,.K5 I I83 w ZOO FIG-4 r WINICIm H Mcgeu I Inventors Robert E. Nelson, Jr.

By /& Attorney United States Patent 3,078,918 GAS DETECTOR FOR STEAM CGNDENSATE AND CGOLING TDWER WATER SYSTEMS William Henry Magearl and Robert Emmett Nelson, Jr.,

Baton Rouge, La., assignors to Esso Research and En-,

gineering Company, a corporation of Delaware Filed Feb. 18, 1957, Ser. No. 640,746 2 Claims. (Cl. 1652) This invention relates to a method of and apparatus for detecting leakage of gases from a vessel or a unit into a steam system and/or cooling water system. It relates more particularly to a method and apparatus for detecting the leakage of pentanes and lighter hydrocarbons in a plant process into a steam condensate system and/or a cooling water system.

In many plant processes, steam is used as the heating medium in heaters or heat exchangers. The heater normally may consist of a series of substantially parallel tubes with heat conductive walls spaced within a larger pipe or vessel. The larger vessel is usually substantially insulated. The fluid to be heated normally passes through the tubes and the steam passes around the tubes through the space within the larger pipe or vessel not occupied by the smaller parallel tubes. By indirect contact, heat is transferred from the steam to the fluid. It is understood that other type heaters may be used. If the walls of the smaller parallel tubes develop leaks or holes therein, either the steam will flow into the stream of fluid being heated or the fluid being heated will flow into the steam system depending upon the pressure differential. If the pressure of the stream of fluid being heated is greater than the pressure of the steam, the steam will become contaminated. In petroleum refining processes quite frequently a stream of pentanes and lighter hydrocarbon is under higher pressure than the steam used for heating. If a leak occurs in the walls of the tubes separating the steam and hydrocarbons, the steam system will become contaminated by the hydrocarbons. This is highly undesirable. An appreciable amount of hydrocarbons in a steam system develops a hazardous situation which may result in fire or explosion. The loss of hydrocarbon is costly and results in waste of a natural resource.

If cooling of a plant stream is desired, a cooler may be used similar to the heater above-described by passing cooling water through the interior space around the tubes and not occupied by the tubes rather than steam. When a leak occurs, loss of the fluid of the plant stream will occur if the pressure of the plant stream is greater than the pressure of the cooling water. If the plant stream is a hydrocarbon, a hazard to safety also arises.

It is readily apparent that it is extremely important to detect as soon as possible any leakage of gases into the steam system and/or cooling water system. This invention discloses a method and apparatus for detecting such leakage and provides means for actuating an alarm.

It is an object of this invention to provide a method and apparatus for detecting the presence of gas in a steam system or cooling water system. A small portion or sample of water is continuously withdrawn from the cooling water system or steam condensate system and is collected in a confined collection zone or enclosed chamber having an upper vapor or gas section and a lower liquid section. A vented seal line or U-tube overflow line is in communication with the liquid section, and is arranged to maintain a high liquid level in the collection zone. A restricted bleed or air vent is provided in the upper portion or top of the collection zone to bleed off the very small quantities of dissolved air or other gases that may normally be present in the water and which comes out of solution. In the event that vapor or gas "ice enters the collection zone at a rate greater than the capacity of the vent or bleed in the upper portion of the chamber, the water level will fall. This drop or variation in level exhibits a change in the volume of gas accumulated in the collection zone and is utilized to actuate an alarm.

The nature and objects of this invention will be more clearly understood from the ensuring description when taken in conjunction with the accompanying drawings in which:

FIG. 1 shows a diagrammatic flow plan including two embodiments of gas alarm apparatus of the present invention for detecting gas in a cooling water system and steam heating system and its application to a typical tower in a simplified flow plan of an alkylation unit;

FIG. 2 represents an enlarged vertical longitudinal sectional view of the float operated device used in connection with the cooling water system;

FIG. 3 represents an enlarged vertical section of a condenser used in connection with the steam heating systern; and

FIG. 4 represents an enlarged vertical section of the displacer element operated device used in connection with the steam heating system.

In FIG. 1, the flow plan of a portion of an alkylation unit is shown to illustrate a practical application of the detecting system. Alkylation is a catalytic reaction involving the addition of a molecule of an isoparaffln to an olefin. In the conventional alkylation process, isobutane is added to propylene, butenes or pentylenes or mixtures thereof, to produce high octane aviation gasoline components. Sulfuric acid is commonly employed as the catalyst in this type of alkylation reaction.

Feed line 10 supplies hydrocarbon feed stock to the lower portion of depropanizer tower 12 with the pressure in tower 12 being between about 200 to about 350 p.s.i.g. Line 14 connects the top portion of depropanizer 12 with cooler or condenser 16 which in turn is connected to reflux drum 18 by line 20. from the top portion of reflux drum 18 by line 21 containing valve 21'. Line 22 connects the bottom of the reflux drum 18 with the upper portion of depropanizer tower 12 for supplying reflux liquid to the tower 12. A pump 23 is used in line 22 to return reflux liquid to tower 12. Valve 25 is in line 22 and regulates the flow of reflux to tower 12.

Heat is supplied to tower 12 by reboiler 24 which is connected to the lower portion of depropanizer tower 12 by line 26 and to the bottom portion by line 28. Line 30 containing valve 31 is a branch from line 22 and connects with cooler 32. Valve 31 regulates the amount of liquid propane that passes through cooler 32 and is discharged through line 33 to be utilized for other uses. Line 34 con meets the bottom portion of depropanizer tower 12 with cooler 36 which is connected by line 38 to a caustic wash unit diagrammatically illustrated at 40. Line 42 connects caustic wash unit 40 to a reaction section 44 which in this case is an alkylation unit. Additional portions of the feed preparation section and fractionation section of the alkylation unit are not shown as they are not essential to an understanding of the present invention.

In a commonly used depropanizer tower of a typical alkylation unit, a feed stream containing propane and isobutane is fed through line 10 to depropanizer tower 12. Heat is supplied to the bottom portion of tower 12 by heater or reboiler 24. Steam from main steam supply line 46 is supplied to reboiler 24 by line 48 with the steam and steam condensate leaving reboiler 24 through lines 50 and 52 and some being passed to a second gas detecting means to be later described. The rest of the steam condensate is returned to the steam boiler (not shown). Overhead product consisting primarily of propane is removed from de- Vapors or gas is removed propanizer tower 12 and is cooled in cooler or condenser 16 which is supplied with cooling water by line 53 from cooling water main 54 which supplies cooling water from a cooling tower not shown. Discharge water from cooler 16 is returned to the cooling tower (not shown) via discharge line'56 and cooling water return main 58.

A part of the reflux liquid from reflux drum 18 is recirculated through line 22 to the upper portion of depropanizer 12. Propaneflows through line 30 from line 22 to cooler 32 which is supplied with cooling water by line 60 from cooling water main 54. Discharge water flows through line .62 from cooler 32 to flow to cooling water return main 58. Propane may be removed from the alkylation unit through line 33 which leads from cooler 32. The bottom productfrom tower 12, which is primarily isobutane, is removed through line 34. The bottom-product is cooled in cooler 36 which is provided with cooling water .by line 66 from cooling water main 54. Discharge water from cooler 36 flows through line 65 to cooling water return main 58. After the bottom product has been cooled in cooler 36 it flows through caustic wash unit 40 to reactor section 44.

An olefin suchas butylene is fed to reactor section 44 through line 61 from a source not shown. Sulfuric acid is fed through line 63 to recycle line 65 which is provided with pump 65. The product from reactor section 44 is removed through line 67 and is a product emulsion containing alkylate, sulfuric acid and unreacted isobutane. The alkylate is primarily isooctane with minor'amounts of other branched chain hydrocarbons. The acid is removed from the hydrocarbon stream by use of a settler (not shown) and a caustic wash unit (not shown). The hydrocarbon stream is then fractionated in a fractionatoi (not shown) to yield finished aviation alkylate blending agent.

In the conventional operation of an alkylation unit, the. pressure within the depropanizer tower 12 is normally between about 200 to 350 p.s.i.g'. The temperature in the bottom portion of the depropanizer tower 12 is normally; between about 180. F. and 250. F. and the temperature in the top portion is normally between about 120 F. to 140. F. The steam used in reboiler 24 is normally be tween about 100 to about 200 p.s.i.g. The pressure of the cooling water in line 54is between. about 60: and 70 p.s.i.g.

A small, continuous sample of water is taken from. a tap at 70 in the cooling water returnv main 58 and passed through. line 72 which i's'provided with a T 74, valve 76- andtorifice union 78. Valve 76 is used for closingline. 72 when adjustments or repairs are required. Orifice union 78 with a & orifice is used to control or restrict the amount ofiwater taken from cooling water return main 58. An orifice union is a pipe coupling machined to retain a thin disc with a small hole to restrict flow of fluid through the pipe. Amanual. check comprising a valve 80, nipples 82, and. 84, L 86. and nozzle 88.is provided atT 74 and servestocheck on water flow in line 72. Water is passed through orifice. union 78 via expanding nipple 90, T92 and. nipple 94, into the bottom of enclosed float chamber 9.6 at 98: of a modified liquidlevel contr'ol' instrument or transmitter 100.shown in greater detail in FIG. 2. i

A vented. U-tube overflow. or seal line 102 extends laterally from T 92 and is vented at its top at 104through vent line 105, and .is arrangedto maintain. a substantially. constant high water. level as indicated at 103 in float chamber 96. Seal line 102 also serves as a discharge to line lflfilwhichfretums tothe cooling tower (not shown). A capillary bleed line 108 having an orifice union 108'- provided with a pin hole orifice extends from the top of enclosed float chamber 96 andis provided to bleed ofi? very small. quantities of air or other gases which collect in the upper portion of transmitter 100.on release from the water. These gases are normally present or dissolved in water. The gases collect in space 103." above level 103-so that float chamber 96 is nearly completely filled with water to level103. Line 108 has a sealed or tight fit in the opening of float chamber 96 with any suitable coupling. Junction 109 of line'106 and U-tube or seal line 102, under normal operation, controls and is at the same height or elevation as liquid level 103 in enclosed float chamber 96. This high level is normally maintained by U-tube overflow 102 connected to the bottom portion of float chamber 96 and vented to prevent siphoning action. Vented seal line or U-tube overflow 102 and discharge line 106 may be arranged to provide for raising or lowering level 103.

In the event gases enter float chamber 96 at a rate greater than the capacity of the capillary or orifice bleed 108 to remove them, the water level 103 of float chamber 96 will be forced down due to the accumulation of gases in the upper portion of chamber 96. Referring now to FIG. 2, a vertical section of modified liquid level transmitter 100 is shown. Similar elements are designated by the same reference characters in each of FIGS. 1 and 2. The transmitter 100 may be any conventional liquid level transmitter. Specifically the liquid level transmitter as shown in one manufactured by Moore Products Company, H and Lycoming Streets, Philadelphia 24, Pennsylvania, and illustrated in their bulletin 2503, copyright 1942 and identified more specifically as Stock Model 24 c 415C on page 10 of said bulletin 2503. The displacer or float 110 is mounted on a short float arm 112 which is connected to the free end of a flexible shaft 114. Shaft 114 extends through wall 114' of float chamber 96 and is in sealed relation therewith. The actual float motion in transmitter 100 as described above is rather small being approximately ,5, It is primarily a change in force which results from the buoyancy of the float 110 which operates transmitter 100. This change in force is transmitted by. stiff tongue 116 arranged within flexible shaft 114 and extending beyond wall 114' to actuate pilot 118. A bracket having limit stops 119 keeps flexible shaft 114 well within its elastic limit as for example whennormal. water lever 103 is above float 110 as shown in FIG. 2.

When gas is present in the cooling water and gas enters float chamber 96 at a rate greater than the capacity of the capillary or orifice bleed 108, such as may be caused by a leak in a cooler or condenser such as coolers 16,. 32, and 36 because the pressure of the plant stream fluid is greater than the cooling water pressure, the water level 103 of float chamber 96 will fall due to the accumulation of gasin the upper portion of the float chamber 96. The force resulting from the change in buoyancy of float 110 caused by the lowering of water level 103 to dotted line position 103', for example is transmitted bythe stiff tongue.116.to actuate air pilot'118. That is, there willbe. a, slight lowering of the float 110 which is transmitted to tongue. 116 to actuate pilot 118. An air supply of approximately. 20 p.s.i.g. is supplied to air pilot 118 byline 120. When pilot 118 is actuated; the air pressure is increased in line 122 which transmits the pilot output air pressure. to an alarm unit 123 adapted to be actuated by. a change in. air pressure.

In an. actual installation, line 72 was O.DE pipe, orifice union.78 was provided'with a orifice-which permittedwater to flow therethrough at the rate of approximately. 2.5 gallons per minute, nipple expanded from /1.- inch tol /z inches which wasthe size of the fitting in thebottom of liquid level controller 100, line 102 was 1 inch O.D., being fitted to 1% inch T 92by areducer not shown, andvent line 105 was /2 inch O.D. Orifice union 108 was /2 inch in size and had a pin holeorifice of & inch in diameter. The liquid level transmitter or controller was made by Moore Products Company as specifically, described above with chamber 96 being mostly cylindrical in shape with the vertical dimension being approximately. Sinches and the horizontal length about 12 inches and having a volume of about 0.20 cubic foot. In a test of this device air was injected into line 58 of the cooling water system at the point designated124 on the drawing. The air was detected and the alarm was sounded in approximately five minutes. The alarm was located in control room and consisted of a horn and signal lights, and was actuated by a sequential switch such as illustrated and described in Mason-Neilan catalog No. 405, page 43, dated August 1954. The time required to detect a gas leak will of course depend among other factors upon the rate or quantity of gas contaminating the water and the size of the cooling system. It is of course understood that other type pilots or switches such as a micro switch may be used in place of air pilot 118.

Referring back to FIG. 1, in a different embodiment of this invention, steam condensate containing some steam from reboiler 24 is passed through line 52 to steam condensate drum 128. The upper portion of condensate drum 128 provides a vapor or steam space and liquid water collects in the lower portion of the drum. A conventional liquid level controller 130 controls the level of water in condensate drum 128 by operating motor or control valve 132 which controls the output of pump 134. The discharged water from pump 134 is normally returned to the boiler (not shown) for reuse. Steam or vapor from the vapor space of steam condensate drum 128 is passed through line 136' to steam blowdown drum 138 which is provided with a stack 140 for discharging steam to the atmosphere and a vented seal line or U-tube overflow 142 connected to the bottom of blowdown drum 138 to maintain a water level 141 in blowdown drum 138 and to provide means for discharging water therefrom at substantially atmospheric pressure. The U-tube overflow or vented seal line 142 connected to the bottom of blowdown drum 138 is provided with a vent at 144 to the atmosphere to prevent siphoning action. Seal line 142 and vent 144 are so arranged and designed to maintain the desired level as at 141 in blowdown drum 138.

A small continuous sample of steam is taken from the upper portion of steam blowdown drum 138 through a tap located at 146 and passed through line 148 into condenser 150 shown in detail in FIG. 3. Plug 151 is located in the top of condenser 150 and may be opened to serve as a manual bleed for condenser 150 when needed. Orifice union 152 is in lIne 148 and is used to regulate the amount of steam taken from blowdown drum 138. Line 148 is provided with valve 154 for shutting off the flow of steam to condenser 150 when desired. Line 156 is used to provide cooling water for coil 158 (FIG. 3) of condenser 150 with water being discharged therefrom through line 160. FIG. 3 illustrates a cross section of condenser 150, showing coil 158 enclosed in a chamber 162 formed by housing 164 and top flange 166 secured thereto. A threaded opening or other means are provided at 168 and 170 for connecting line 156 and 160 respectively to coil 158. Line 148 is connected to condenser 150 at 172 which may be by a conventional threaded joint.

Steam or water vapor enters that portion of chamber 162 not occupied by coil 158 or exterior to coil 158 and upon coming in indirect contact with the cooling water inside coil 158, the steam will be totally condensed. Condensate or water will flow out through a bottom opening 174 which is shown threaded and is connected to line 176 (FIGS. 1 and 3) which permits the condensate to fiow into the side of enclosed displacer or float chamber 178 of a modified liquid level controller or transmitter 180 shown in detail in FIG. 4. A vented seal line 182 which functions as a U-shaped line extends laterally from the lower portion of chamber 178 and is provided with vent line 184 which may be in the form of an inverted U-tube with a vent at 185. Horizontal line 189 extends from seal line 182 intermediate its ends to maintain a substantially constant high water level 183 in chamber 178. Seal line 182 also serves as a discharge to line 189 which discharges the water to a sewer. The water level 183 will be determined by the elevation at junction 191 of vented seal line 182 and discharge line 189. A capillary bleed is provided in orifice union 186 at the outer end of vent line 187 which extends from the top of enclosed chamber 178 and is provided to bleed 011 small quantities of air or other noncondensables that may normally be present in the steam and which collect in the upper part of chamber 178. This will permit chamber 178 to maintain a constant high water level 183 as determined by arrangement of vented seal line 182 and discharge line 189 which normally permits chamber 178 to be filled with water or condensate to a level 183 with normally only a rather small gas space or section in the upper portion.

In the event that gases enter chamber 178 at a rate greater than the capacity of the capillary bleed 186 which is connected to the top of chamber 178 by line 187, the water level of chamber 178 will be forced down by the accumulation of gases in the upper portion of the chamber 178. If a leak should develop in the coils of heater or reboiler 24, for example, the hydrocarbons, being normally under higher pressure than the steam, would flow into and contaminate the steam and would accumulate in the upper portion of chamber 178. Liquid level controller or transmitter may be any liquid level transmitter. Specifically the liquid level transmitter 180 as shown is one manufactured by Mason-Neilan Regulator Company, 1190 Adams Street, Boston 24, Massachusetts and illustrated in their catalog No. 405 dated August 1954 and described more specifically as Model 12820 with specifications and detail descriptions shown therein on page 25.

FIG. 4 shows an enlarged vertical section of the displacer element operated device 180 used in connection with the steam heating system. Displacer element 188 is suspended by hanger 190 from torque arm 192 which is secured to torque tube plate 194. Hanger 190 is rigidly secured to the top of element 188 and is inverted J-shaped. Torque arm 192 has an inverted V-shaped notch at 195 supported on knife edge 196. Torque tube plate 194 is secured to a torque tube assembly (not shown) which has a bias in the direction of arrow 197 which is opposite from the downward direction of the force exerted by the effective Weight of displacer element 188. Although displacer element 188 will rise and fall with level changes, its movement is substantially less than the actual level movement.

As the liquid level 183 changes, the net weight of dis placer element 188 varies and this change in net weight is transmitted through a torque tube (not shown) secured to plate 194 to actuate an air pilot or control mechanism 198 or other type switch and is arranged to actuate the air pilot only when the liquid level lowers. Line-200 with valve 202 permits drainage of chamber 178. An air supply of approximately 20 p.s.i.g. is supplied to air pilot or control mechanism 198 by line 204. The torque tube assembly (not shown) transmits the angular motion of the torque tube which is a reflection of the change in liquid level 183 to the controller mechanism 198 which is shown in detail on pa e 25 of said Mason-Neilan catalog No. 405. A reversing slotted arc plate in mechanism 198 serves as a motion take-off arc plate from the torque tube. A control link in mechanism 198 is mounted on the arc plate and a lowering of liquid level 183 to dotted line position 183', for example, lowers the control arm in mechanism 198 allowing a flapper to cover an air nozzle within the control mechanism 198 with a resulting increase in output air pressure in line 206. When pilot or control mechanism 198 is actuated, the air pressure increases in line 206 which transmits the control mechanism air output pressure to an alarm unit 208 (horn and light) adapted to be actuated by the increase in air pressure. Line 206 may be connected to alarm unit 123 or a central alarm unit, if desired.

Modified liquid level transmitter 100 as above described may be substituted for the modified liquid level controller or transmitter 180, and likewise transmitter 180 may be substituted for transmitter 100 with required piping or connecting arrangements being made.

In an actual installation line 148 leading from blowdown drum 138 was A" OD. pipe, orifice union 152 was Line 176 from the to the chamber 178 of modified liquid level controller 180.

;Chamber 178 was-essentially cylindrical and was-about-4 inches in diameter and about 30 inches high in total height. U-tube overflow on vent seal line 182 was 1'' OD. pipe with ventline-184 being A" O.D..pipe. Vent line 187 was A inch standardpipe and o'rificeunion-186 was size 3/2 inch standard pipe and had a capillary bleed-hole of ,4 inch-in diameter. The liquidlevel controller 180 was :made by Mason-Neilan -Regulator Companyas above described. in a test of this device propane-was injected into the steam condensate drum'128. The propane was detected and'the alarm which was located in the control .room was sounded-in approximately three minutes.

his to be understood that various changes in shape,

size and arrangement of the different elements may be resorted -.to without departing from the spirit of the invention or the scope of the subjoined claims.

What is claimedis; l '1. An apparatus of the character described for detecting a loss of hydrocarbon gases from a unit processing hydrocarbons under pressure where a heat exchange fluid in a heat exchange system is under lower pressure than .said unit and accumulation of hydrocarbongas may occur in-said heat exchange fluid, including, in combination, an indirect heat exchanger for hydrocarbons under pressure, ,a heat exchange system including a source of heat exchange fluid connected to said-heat exchanger, means for continuously removing a small portion of said heat exchange fluid from said system after said heat exchange fluid has passed through said heat exchanger, :1 chamber communicating with said means and receiving said small portion of heat exchange fluid as a liquid and any escaped hydrocarbon gas present therein, a restricted vent in the top of said chamber for allowing the escape of non'con'densable gas normally present, means for maintaining the liquid fluid in said chamber, a floatable displacer element in said chamber and adapted to be actuated by the liquid fluid level in said chamber, an air line outside said chamber, a valve in said air line, an alarm system associated with said air line, means actuated by said fl-oatable displacer element for actuating said valve in'said air line for actuating said alarm when there is an undue collection of hydrocarbon gas in said chamber whereby the liquid fluid level is depressed to such an extent that the floatable displacer element is moved from a normal position.

2. A method of detecting hydrocarbon gas in a cooling water or steam condensate system comprising continuously withdrawing a small portion of water from the system, collecting said portion of water in a confined collection zone having an upper gaseous section and a lower liquid section, continuously discharging said portion of water from said lower liquid section through a vented seal line thereby maintaining a constant level of water in said lower liquid section, continuously maintaining fluid communication between the Withdrawn water and the collection zone, collecting gas in the upper gaseous section of said collection zone as the gas is released from the water in said collection zone, discharging gas from said upper gaseous section of the collection zone at a substantially constant flow rate whereby under normal operating conditions the amount of gas being discharged equals the amount of gas being released from said water in said collection zone, depressing said water level in said References Cited in the file of this patent UNITED STATES PATENTS 651,857 Hill et al. June 19, 1900 1,915,576 Mullen June 27, 1933 2,281,125 Wiemer Apr. 28, 1942 2,547,526 Hilliard Apr. 3, 1951 2,626,386 Raby Jan. 20, 1953 2,669,435 Cord et al. Feb. 16, 1954 2,679,641 Liles May 25, 1954 2,701,355 Rinehart et al. Feb. 1, 1955 2,713,973 Hencken et al. July 26, 1955 2,714,715 Manier Aug. 2, 1955 2,717,989 Bossard Sept. 13, 1955 2,728,070 Kelly Dec. 20, 1955 2,736,013 Binford Feb. 21, 1956 2,748,378 Feins May 29, 1956 2,808,581 Findlay Oct. 1, 1957 2,893,701 Bell July 7, 1959 

2. A METHOD OF DETECTING HYDROCARBON GAS IN A COOLING WATER OR STEAM CONDENSATE SYSTEM COMPRISING CONTINUOUSLY WITHDRAWING A SMALL PORTION OF WATER FROM THE SYSTEM, COLLECTING SAID PORTION OF WATER IN A CONFINED COLLECTION ZONE HAVING AN UPPER GASEOUS SECTION AND A LOWER LIQUID SECTION, CONTINUOUSLY DISCHARGING SAID PORTION OF WATER FROM SAID LOWER LIQUID SECTION THROUGH A VENTED SEAL LINE THEREBY MAINTAINING A CONSTANT LEVEL OF WATER IN SAID LOWER LIQUID SECTION, CONTINUOUSLY MAINTAINING FLUID COMMUNICATION BETWEEN THE WITHDRAWN WATER AND THE COLLECTION ZONE, COLLECTING GAS IN THE UPPER GASEOUS SECTION OF SAID COLLECTION ZONE AS THE GAS IS RELEASED FROM THE WATER IN SAID COLLECTION ZONE, DISCHARGING GAS FROM SAID UPPER GASEOUS SECTION OF THE COLLECTION ZONE AT A SUBSTANTIALLY CONSTANT FLOW RATE WHEREBY UNDER NORMAL OPERATING CONDITIONS THE AMOUNT OF GAS BEING DISCHARGED EQUALS THE AMOUNT OF GAS BEING RELEASED FROM SAID WATER IN SAID COLLECTION ZONE, DEPRESSING SAID WATER LEVEL IN SAID COLLECTION ZONE UPON THE ACCUMULATION OF EXCESS GAS IN SAID UPPER GASEOUS SECTION AND UTILIZING THE EXCESS GAS THROUGH ITS DEPRESSION OF THE WATER LEVEL TO SOUND A WARNING. 